Magnetic wedge.



PATENTED DEC. 3, 1907.

S. R. BERGMAN. MAGNETIC WEDGE. APPLwA'noH FILED APB.10.1907.

Inventor Sven R. Ber man,

Wltnesses:

9, all;

for retaining: conductors in slots formed in UNITED sTATEs PATENTOFFICE.

SVEN'R. BERGMAN, or LYNN,- MASSACHUSETTS,

A CORPORATION ASSIGNOR TO GENERAL ELECTRIC COMPANY, OF NEW YORK.

MAGNETIC WEDGE.

. Specification of Letters Patent.

Application filed April 10. 1907- Serial No. 367.323.

the corestructures and it has for its object to improve such devices.

p In induction motors, for example, it is advantageous to have a substantially unbroken I5-surface of magnetic material adjacent the air gap between the stator and rotor, in order to produce a uniform distribution of the flux and decrease the reluctance of the air gap. It is therefore desirable that the retaining devices for'the coils be made of magnetic material; and, in order to prevent losses due to eddy currents in the retaining devices, the magnetic material should be finely divided. W

-I have found that a bundle of him or steel wires suitably insulated 'from each other makes a very satisfactory," retaining wedge. Such a wedge may be produced by rolling up a strip of iron or steel cloth until a desired 8'0 mass is obtained and then forcing the mass into the proper form tofit the slots Within which the conductors lie. The cloth is preferably annealed and then japanned before it is rolled up, whereby the successive layers are thoroughly insulated from each other without, however, producing any consider able gap between the portions of magnetic material. \Vhen the wedges are put in place they are insulated from the core struc- 40 ture-ln a thin layer of insulating material such as varnished paper, in order to prevent short-circuiting the laminae.

The various features of novelty which characterize my invention will be hereinafter articularly pointed out in the claims; but or a full understanding of the invention and of its various objects-and advantages, refer once may be had to the following detailed description taken in connection with the accompanying drawing, wherein:

Figure 1 shows, in process of construction, a magnetic wedge constituting a preferred form of the present invention; Fig. 2 is a perspective viewof the insulation which sepa- 56 rates the wedge from the core properwhen the wedge is placed in position in a machine; and Fig. 1) is a perspective view of a fragment of a stator core of an induction motor having the coils. held in place by means of my improved wedges.

' Referring to the drawing, 1 indicates a stator core structure having slots 2 which The conductors do not extend quite to the top of the slots, and at points just above the conductors are under-cut slightly,

contain coils or conductors 3.

the walls of the slots as at 4.

5 and 5 are wedges, each of Which'is erably one-half as long as the width Patented Dec. 3, 1907.

core, and of a width and thickness such that when they are driven into the slots above the,

coils, they completely fill the slots and the or surunder-cut portions and have their out faces flush. with the face of the core. of the wedges consists of a bundle l lach of annealed iron or steel wires securely held to gether, the whole being surrounded on three sides by a strip of'msulatmg material '7,

formed of varnished paper or the like The insulation prevents the wedge from shortcircuiting the core.

I have found that the magnetic portion of thewedge may be conveniently constructed when. the wires are wound up upon a mandrel.

'in the form oi iron or steel cloth, the cloth -bemg'iirst apanned and then rolled or The mandrel is then removed and the tube which remains is placed in a steel mold and forced into a compact mass.

The japan thoroughly insulates the layers of cloth from each other without mterposing any considerable gap mthe magnetic path.

Alter the wedge has been forced into shape, the covering of insulation is secured thereto in any suitable way, as,

for example, by means of Shellac.

\Vhat I. claim as new and desire to by Letters Patent of the United States, is-

i '1. As an article of manufacture, a slotclosing device consisting of a bundle of wires fastened together and insulated from each other.

2. As an article of manufacture,

a slot 7 closing device consisting of a roll of magnetic cloth having insulating material between the convolutions.

As an article of manufacture, a slotclosing device consisting of a roll of japanned magnetic cloth.

4. As an article of manufacture, a slotclosing device comprising in combination a bundle of wires fastened together and insulated from each other and a strip of insulat: ing materialipartially surrounding the said bundle.

'5. As an article of manufacture, a slotclosing device comprising in combination a roll of magnetic cloth having insulating material between the convolutions, anda strip of insulating material partially surrounding the said device.

6. As an article of manufacture, a slot. closing, device comprising in combination a roll of japanned magnetic cloth, and a strip of insulating material partially surrounding the said roll:

7. In a dynamo electrlc machine, a core having coil-receiving slots and slot-closing.

devices comprising n combination rolls.of

.magnetic cloth, and strips of insulating material partially surrounding said rolls.

my hand this sixthday of April, 1907.

SVEN R. BERGMAN. Witnesses:

JOHN A. MoHANUs, Jr., v PHILIP F. HAItRiNG-TQN.

In witnesswhereof, Ijhave hereunto set 

